The present invention relates to a Diesel engine fuel injection device having a detector for detecting the actual time of combustion from the flame caused by the combustion of mixture.
In the Diesel engine, in order to produce its power output efficiently, the timing of fuel injection must be varied in accordance with the magnitude of the engine speed and load, for example, To accomplish this, the actual time of injection must be detected. In the past, a method of detecting the actual time of fuel injection has been proposed in which the occurrence of a flame is used as an actual injection time signal by means of a combustion detector disposed in the cylinder. Although this method is advantageous in that there is no need to provide compensation for the injection system, the ignition lag in the engine, etc., and that the accuracy of the actual injection timing with respect to the desired injection timing is improved, the detector for detecting the flame comprises a photoelectric transducer, e.g., a phototransistor mounted to face a hole formed in the cylinder through the intermediary of a light transmitting material such as glass and thus there is a disadvantage that soot is deposited on the surface of the glass exposed to the inside of the cylinder as the engine is operated over a long period of time and the light transmission properties are deteriorated thus gradually degrading the detection sensitivity and eventually making it impossible to detect the flame.